Paleomagnetic constraints on the assembly of the Old Red Continent

Abstract

A model is proposed on the basis of paleomagnetic and geological arguments for the assembly of the Old Red Continent, which in the Devonian comprised North America, the Baltic Shield and Russian platform, as well as a third element called "Armorica". The latter is thought to have included most of Hercynian Europe and southern England and Wales, as well as possibly the Avalonian terranes of northeastern North America and perhaps some parts of the Atlas ranges and Moroccan Meseta. The model envisions a Late Ordovician (Taconic) collision of North America and Armorica, which are joined in the Late Silurian by the Baltic Shield and Russian platform. Not until the late Early Carboniferous did Gondwana join the Old Red Continent in a collision responsible for a large internal megashear parallel to the Caledonian orogenic belt as well as the Hercynian-Alleghenian orogeny. Subduction of the large Siluro-Devonian ocean between Gondwana and the Old Red Continent is held responsible for the mid-Devonian Acadian orogeny.